Adhesive tapes and articles

Abstract

This invention provides an adhesive tape with excellent stress absorption properties, having an active energy ray curable adhesive layer that exhibits excellent adhesive properties such as 180° adhesion, shear adhesion, and shear holding power when applied to adherends made of general-purpose materials with a wide range of polarities, such as metals and polyolefins. [Solution] An adhesive tape comprising a foam substrate and an adhesive layer provided on at least one surface of the foam substrate, wherein the adhesive layer contains an active energy ray curable adhesive composition, the active energy ray curable adhesive composition comprising a urethane (meth)acrylate resin (A) having an acryloyl group equivalent of 5000 to 40000, obtained by reacting a polyol (a), a polyisocyanate (b), and a (meth)acrylic compound (c) having a hydroxyl group, a nitrogen atom-containing (meth)acrylic monomer (B) capable of forming a homopolymer with a glass transition temperature of 15°C or higher, a (meth)acrylic monomer (C) capable of forming a homopolymer with a glass transition temperature of -15°C or lower, a photopolymerization initiator (D), and an HSP value of 12 (J / cm²). 3 ) 0.5 More than 21(J / cm 3 ) 0.5 An adhesive tape containing the following tackifying resin (E).

Description

[Technical Field]

[0001] The present invention relates to adhesive tapes and articles. More specifically, the present invention relates to adhesive tapes having an active energy ray curable adhesive layer, applicable to various fields such as the manufacture of electronic devices and automotive components, and articles having a structure bonded by the adhesive tape. [Background technology]

[0002] UV-curing adhesives typically do not contain solvents such as organic solvents or water, and do not require a solvent removal process when forming the adhesive layer. In particular, compared to using organic solvents, they eliminate the energy used for the production, transportation, and drying of organic solvents, and also reduce carbon dioxide emissions caused by incinerating solvents during removal. Furthermore, because they do not require a maturation period to form a three-dimensional cross-linked structure, they are attracting attention from the perspective of improving the energy efficiency and production efficiency of final products manufactured using adhesives, as well as considering environmental factors. Various studies have been conducted to improve the adhesive strength of UV-curable adhesives. For example, Patent Document 1 proposes an active energy ray-curable adhesive composition containing two types of ethylenically unsaturated monomers, a heterocyclic monomer and a hydroxyl group-containing monomer, in specific ratios, which is said to have a good balance of adhesive strength and heat and humidity resistance. Patent Document 2 proposes an adhesive composition containing a specific urethane (meth)acrylate, a monofunctional monomer having a nitrogen atom and an unsaturated bond, and a monofunctional (meth)acrylate having a hydroxyl group, which is said to have excellent foaming resistance and be able to maintain adhesive strength even in high temperature and high humidity environments. Patent Document 3 proposes a resin composition for UV-curable adhesives containing a specific (meth)acrylic monomer capable of forming a homopolymer with a predetermined glass transition temperature in a specific ratio, which is said to be able to achieve both adhesive strength and holding power. Patent Document 4 proposes a resin composition for UV-curable adhesives containing a urethane (meth)acrylate resin having a specific range of (meth)acryloyl group equivalents. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] International Publication No. 2016 / 013510 [Patent Document 2] Japanese Patent Publication No. 2017-186450 [Patent Document 3] Japanese Patent Publication No. 2012-136557 [Patent Document 4] Japanese Patent Publication No. 2014-005368 [Overview of the project] [Problems that the invention aims to solve]

[0004] The compositions disclosed in Patent Document 1 and Patent Document 2 both contain hydroxyl group-containing monomers as ethylenically unsaturated monomers, but since such monomers are skin irritants, there is room for improvement in terms of the handling properties and safety for the human body of the compositions. On the other hand, adhesive tapes are used in various industrial fields such as office automation equipment, IT products, home appliances, and automobiles as a reliable bonding method with excellent workability, for fixing parts, temporarily fixing parts, and as labels to display product information. These parts and products are often made of metal or resin, and in recent years, adhesive tapes have been required to have good adhesive properties for a wide range of general-purpose materials such as metals and polyolefins, as well as impact resistance that can absorb stress between parts and products. Therefore, there is a need for an adhesive tape that has an adhesive layer with adhesive properties even better than those disclosed in Patent Documents 1 to 4, which are required for automotive parts and the like, and that also has excellent stress absorption (impact resistance) functionality.

[0005] The present inventors have discovered that the above problems can be solved by an adhesive tape having an adhesive layer provided on at least one surface of a foam substrate, made from an adhesive composition containing a specific urethane (meth)acrylate resin, a specific monomer, and a specific tackifying resin, and have arrived at the present invention. In other words, the object of the present invention is to provide an adhesive tape with excellent stress absorption properties, having an active energy ray curable adhesive layer that exhibits excellent adhesive properties such as 180° adhesion, shear adhesion, and shear holding power when applied to adherends made of general-purpose materials with a wide range of polarities, such as metals and polyolefins. Another object of the present invention is to provide an article having a structure bonded by the adhesive tape. [Means for solving the problem]

[0006] The present invention relates to the following [1] to

[15] . [1] An adhesive tape comprising a foam substrate and an adhesive layer provided on at least one surface of the foam substrate, The adhesive layer contains an active energy ray curable adhesive composition, The above-mentioned active energy ray curable adhesive composition is A urethane (meth)acrylate resin (A) having an acryloyl group equivalent of 5,000 to 40,000, obtained by reacting a polyol (a), a polyisocyanate (b), and a (meth)acrylic compound (c) having hydroxyl groups, A nitrogen atom-containing (meth)acrylic monomer (B) capable of forming homopolymers with a glass transition temperature of 15°C or higher, A (meth)acrylic monomer (C) capable of forming a homopolymer with a glass transition temperature of -15°C or lower, Photopolymerization initiator (D), HSP value is 12 (J / cm²) 3 ) 0.5 More than 21(J / cm 3 ) 0.5 An adhesive tape containing the following tackifying resin (E). [2] The adhesive tape according to [1], wherein the urethane (meth)acrylate resin (A) is a polyether-based urethane (meth)acrylate resin or a polyester-based urethane (meth)acrylate resin. [3] The adhesive tape according to [1] or [2], wherein the weight-average molecular weight (Mw) of the urethane (meth)acrylate resin (A) is 15,000 or more. (4) The pressure-sensitive adhesive tape according to any one of (1) to (3), wherein the tackifier resin (E) has a softening point of 90°C or higher. (5) The HSP value of the tackifier resin (E) is 15 (J / cm 3 ) 0.5 or more and 21 (J / cm 3 ) 0.5 or less, the pressure-sensitive adhesive tape according to any one of (1) to (4). (6) The nitrogen atom-containing (meth)acrylic monomer (B) has an HSP value of 20 (J / cm 3 ) 0.5 or more, the pressure-sensitive adhesive tape according to any one of (1) to (5). (7) The pressure-sensitive adhesive tape according to any one of (1) to (6), wherein the (meth)acrylic monomer (C) is a monomer having no hydroxyl group. (8) The pressure-sensitive adhesive tape according to any one of (1) to (7), wherein the pressure-sensitive adhesive layer has a biomass carbon content of 20% or more as measured in accordance with ASTM D6866 Method B. (9) The pressure-sensitive adhesive tape according to any one of (1) to (8), wherein the foam substrate has a 25% compressive strength of 10 kPa or more. (10) The foam substrate has an apparent density of 0.05 to 0.75 g / cm 3 , the pressure-sensitive adhesive tape according to any one of (1) to (9). (11) The pressure-sensitive adhesive tape according to any one of (1) to (10), wherein the foam substrate has a tensile elongation at break in the machine direction of 100% or more, and a tensile elongation at break in the transverse direction of the foam substrate of 90% or more. (12) The pressure-sensitive adhesive tape according to any one of (1) to (11), wherein the foam substrate has a tensile strength at break in the machine direction of 15 MPa or more and 60 MPa or less, and a tensile strength at break in the transverse direction of the foam substrate of 10 MPa or more and 50 MPa or less. (13) The pressure-sensitive adhesive tape according to any one of (1) to (12), wherein the foam substrate has a biomass carbon content of 30% or more as measured in accordance with ASTM D6866 Method B.

[14] The adhesive tape according to any one of [1] to

[13] , wherein the biomass carbon content of the adhesive tape, as measured in accordance with ASTM D6866 B, is 20% or more.

[15] An article comprising at least two adherends and an adhesive tape according to any one of [1] to

[14] having the adhesive layer on both sides of the foam substrate, wherein the two adherends are bonded together via the adhesive tape. [Effects of the Invention]

[0007] According to the present invention, it is possible to provide an adhesive tape with excellent stress absorption properties, having an active energy ray curable adhesive layer that exhibits excellent adhesive properties such as 180° adhesion, shear adhesion, and shear holding power to adherends made of general-purpose materials with a wide range of polarities, such as metals and polyolefins. Furthermore, according to the present invention, it is possible to provide an article having a structure bonded by the adhesive tape. [Modes for carrying out the invention]

[0008] The present invention relates to an adhesive tape having a foamed substrate and an adhesive layer provided on at least one surface of the foamed substrate, The adhesive layer contains an active energy ray curable adhesive composition, The active energy ray curable adhesive composition (hereinafter also simply referred to as "adhesive composition") comprises a urethane (meth)acrylate resin (A) (hereinafter also simply referred to as "urethane (meth)acrylate resin (A)") having an acryloyl group equivalent of 5,000 to 40,000, obtained by reacting a polyol (a), a polyisocyanate (b), and a (meth)acrylic compound (c) having a hydroxyl group; a nitrogen atom-containing (meth)acrylic monomer (B) (hereinafter also simply referred to as "nitrogen atom-containing (meth)acrylic monomer (B)") capable of forming a homopolymer with a glass transition temperature (Tg) of 15°C or higher; a (meth)acrylic monomer (C) (hereinafter also simply referred to as "(meth)acrylic monomer (C)") capable of forming a homopolymer with a glass transition temperature (Tg) of -15°C or lower; a photopolymerization initiator (D); and an HSP value of 12 (J / cm²). 3 ) 0.5More than 21(J / cm 3 ) 0.5 The adhesive tape contains the following tackifying resin (E) (hereinafter also simply referred to as "tackifying resin (E)"). Embodiments of the present invention will be described in detail below. In this specification, numerical ranges indicated using "~" represent a range that includes the numerical values ​​before and after "~" as the minimum and maximum values, respectively. In this specification, "(meth)acrylic" is a general term for acrylic, methacrylic, and both thereof. "(meth)acrylate" is a general term for acrylate, methacrylate, and both thereof. First, we will describe the components of the adhesive composition contained in the adhesive layer that constitutes the adhesive tape of the present invention.

[0009] Adhesive composition [Urethane (meth)acrylate resin (A)] The urethane (meth)acrylate resin (A) is obtained by reacting a polyol (a), a polyisocyanate (b), and a (meth)acrylic compound (c) having hydroxyl groups, and has an acryloyl group equivalent of 5,000 to 40,000. The urethane (meth)acrylate resin (A) has (meth)acrylic groups that undergo radical polymerization by light irradiation or heating, and when the equivalent amount of such (meth)acrylic groups, i.e., the acryloyl group equivalent, is in the range of 5,000 to 40,000, a crosslinked structure with excellent cohesive force and flexibility can be obtained, thus achieving both excellent adhesive strength and holding power in the adhesive layer formed from the adhesive composition. The acryloyl group equivalent of the urethane (meth)acrylate resin (A) is preferably 7,000 to 40,000, more preferably 7,000 to 38,000, and even more preferably 7,000 to 35,000. Note that the acryloyl group equivalent means the value obtained by dividing the total mass of the polyol (a), polyisocyanate (b), and (meth)acrylic compound (c) having hydroxyl groups by the equivalent amount of (meth)acrylic groups present in the urethane (meth)acrylate resin (A).

[0010] Examples of polyols (a) that can be used include polyether polyols, polyester polyols, polycarbonate polyols, and polyacrylic polyols. These may be used individually or in combination of two or more types. Examples of polyether polyols include polytetramethylene glycol obtained by ring-opening polymerization of tetrahydrofuran; modified polytetramethylene glycol obtained by copolymerizing tetrahydrofuran with alkyl-substituted tetrahydrofuran or neopentyl glycol; and polyether polyols having an alicyclic structure. Furthermore, as the polyether polyol, a product obtained by addition polymerization of one or more alkylene oxides such as ethylene oxide, propylene oxide, and butylene oxide to a compound having two or more active hydrogens may be used. Examples of compounds having two or more active hydrogens include ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, 1,2-propanediol, 1,3-propanediol, dipropylene glycol, tripylene glycol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 1,5-pentanediol, 1,5-hexanediol, 1,6-hexanediol, 2,5-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, 1,12-dodecanediol, 2-methyl-1,3-propanediol, neopentyl glycol Examples include 2-butyl-2-ethyl-1,3-propanediol, 3-methyl-1,5-pentanediol, 2-ethyl-1,3-hexanediol, 2-methyl-1,8-octanediol, glycerin, diglycerin, trimethylolpropane, ditrimethylolpropane, trimethylolpropane, 1,2,6-hexanetriol, triethanolamine, triisopropanolamine, pentaerythritol, dipentaerythritol, sorbitol, saccharose, ethylenediamine, N-ethyldiethylenetriamine, 1,2-diaminopropane, 1,3-diaminopropane, 1,2-diaminobutane, 1,3-diaminobutane, 1,4-diaminobutane, diethylenetriamine, phosphoric acid, acidic phosphate esters, etc. Among these, polypropylene glycol and polytetramethylene glycol are preferred from the viewpoint that the adhesive layer formed from the adhesive composition easily achieves both excellent adhesive strength and holding power.

[0011] Examples of polyester polyols include condensed polyester polyols and lactone-based polyester polyols. Condensed polyester polyols are reaction products of low molecular weight polyhydric alcohols (such as ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, butanediol, pentanediol, neopentyl glycol, hexanediol, cyclohexanedimethanol, glycerin, 1,1,1-trimethylolpropane, 1,2,5-hexanetriol, pentaerythritol, 1,4-cyclohexanedimethanol, 1,3-propanediol, and sugars such as sorbitol) and polyhydric basic carboxylic acids (such as glutaric acid, adipic acid, azelaic acid, fumaric acid, maleic acid, pimelic acid, suberic acid, sebacic acid, phthalic acid, terephthalic acid, isophthalic acid, dimer acid, pyromellitic acid, oligomeric acid, hexahydrophthalic anhydride, and 1,4-cyclohexanedicarboxylic acid). Examples of lactone-based polyester polyols include polycaprolactone polyols obtained by ring-opening polymerization of lactones such as ε-caprolactone, α-methyl-ε-caprolactone, and ε-methyl-ε-caprolactone.

[0012] Examples of polycarbonate polyols include those obtained by the reaction of carbonates (carbonate esters) such as dialkyl carbonates (dimethyl carbonate, diethyl carbonate, etc.), ethylene carbonate, and diphenyl carbonate with glycols such as diethylene glycol, ethylene glycol, triethylene glycol propanediol, propanediol, butanediol, neopentyl glycol, pentanediol, 3-methyl-1,5-pentanediol, octanediol, 1,4-butynediol, dipropylene glycol, tripropylene glycol, polytetramethylene ether glycol, 2-methyl-1,3-propanediol, 2-ethyl-2-butyl-1,3-propanediol, 1,4-cyclohexanediglycol, and 1,4-cyclohexanedimethanol.

[0013] In the production of urethane (meth)acrylate resin (A), a chain extender containing active hydrogen atoms may be used in conjunction with the polyol (a) described above. Examples of such chain elongators include polyhydric alcohols such as ethylene glycol, 1,2-propanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 3-methyl-1,5-pentanediol, 1,6-hexanediol, 3,3'-dimethylolheptane, 1,4-cyclohexanedimethanol, neopentyl glycol, 3,3-bis(hydroxymethyl)heptane, diethylene glycol, dipropylene glycol, glycerin, trimethylolpropane, sorbitol, and hydroquinone diethylol ether; and polyhydric amines such as ethylenediamine, propylenediamine, hexamethylenediamine, trimethylhexamethylenediamine, isophoronediamine, 4,4'-dicyclohexylmethanediamine, diaminocyclohexane, methyldiaminocyclohexane, and norbornenediamine. These chain elongators may be used individually or in combination of two or more.

[0014] The weight-average molecular weight (Mw) of polyol (a) is preferably in the range of 500 to 80,000, and more preferably in the range of 1,500 to 75,000. Having the Mw of polyol (a) within this range is preferable from the viewpoint of imparting good cohesive strength and flexibility to the adhesive layer formed from the adhesive composition. Note that the Mw of polyol (a) is a standard polystyrene equivalent value measured using gel permeation chromatography (GPC).

[0015] Examples of polyisocyanates (b) include aromatic diisocyanates such as xylylene diisocyanate, phenylene diisocyanate, tolylene diisocyanate, diphenylmethane diisocyanate, and naphthalene diisocyanate; and aliphatic or aliphatic cyclic structure-containing diisocyanates such as hexamethylene diisocyanate, lysine diisocyanate, cyclohexane diisocyanate, isophorone diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, diisocyanate methylcyclohexane, and tetramethylxylylene diisocyanate. These polyisocyanates may be used individually or in combination of two or more. Among these, isophorone diisocyanate and hexamethylene diisocyanate are more preferred from the viewpoint of easily achieving both excellent adhesive strength and holding power in the adhesive layer formed from the adhesive composition.

[0016] The hydroxyl groups in the hydroxyl group-containing (meth)acrylic compound (c) react with the isocyanate groups in the polyisocyanate (b), thereby introducing (meth)acrylic groups into the urethane (meth)acrylate resin (A). Examples of hydroxyl group-containing (meth)acrylic compounds (c) include alkyl esters of hydroxyl group-containing (meth)acrylates such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl acrylate, 3-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, and 6-hydroxyhexyl acrylate; polyfunctional (meth)acrylates containing hydroxyl group-containing compounds such as trimethylolpropanedi(meth)acrylate, pentaerythritol tri(meth)acrylate, and dipentaerythritol penta(meth)acrylate; hydroxyl group-containing acrylamide derivatives such as N-(2-hydroxyethyl)acrylamide; and polyethylene glycol monoacrylate and polypropylene glycol monoacrylate. Among these, 2-hydroxyethyl acrylate, 4-hydroxybutyl acrylate, and N-(2-hydroxyethyl)acrylamide are preferred from the viewpoint of ease of availability, ease of improving the curability of the adhesive composition, and ease of achieving both excellent adhesive strength and holding power in the formed adhesive layer.

[0017] The urethane (meth)acrylate resin (A) is preferably a polyether-based urethane (meth)acrylate resin using at least a polyether polyol as polyol (a), or a polyester-based urethane (meth)acrylate resin using at least a polyester polyol as polyol (a). Using a polyether-based urethane (meth)acrylate resin allows the adhesive layer formed from the adhesive composition to achieve both excellent adhesive strength and holding power, and improves the durability of the adhesive layer, particularly its hydrolysis resistance. The weight-average molecular weight (Mw) of the urethane (meth)acrylate resin (A) is preferably 15,000 or more, more preferably 18,000 or more, and even more preferably 20,000 or more, from the viewpoint of enabling the adhesive layer formed from the adhesive composition to achieve both excellent adhesive strength and holding power by improving cohesive strength, and also having excellent heat resistance and coating workability. The Mw of the urethane (meth)acrylate resin (A) is preferably 100,000 or less, and more preferably 80,000 or less. Note that the Mw of urethane (meth)acrylate resin (A) is a standard polystyrene equivalent value measured using gel permeation chromatography (GPC).

[0018] Urethane (meth)acrylate resin (A) can be manufactured, for example, by the following method. (1) Under solvent-free conditions, the polyol (a) and the hydroxyl group-containing (meth)acrylic compound (c) are mixed, and then the polyisocyanate (b) is added and reacted. (2) Under solvent-free conditions, a polyol (a) and a polyisocyanate (b) are reacted to obtain a urethane prepolymer having isocyanate groups at the molecular ends, and then a hydroxyl group-containing (meth)acrylic compound (c) is added and reacted. In all cases, the reaction temperature is preferably in the range of 20 to 120°C, and the reaction time is preferably 30 minutes to 24 hours. Although a solvent may be present, it is preferable to carry out the reaction under solvent-free conditions because solvent removal is not required when manufacturing the adhesive composition, thus simplifying the process. The reaction between polyol (a), polyisocyanate (b), and hydroxyl group-containing (meth)acrylic compound (c) is preferably carried out within a range of 0.3 to 3.00 for controlling the molecular weight of the resulting urethane (meth)acrylate resin (A). This is because the equivalent ratio [total amount of isocyanate groups / hydroxyl groups] between the total amount of hydroxyl groups in polyol (a) and hydroxyl group-containing (meth)acrylic compound (c) and the isocyanate groups in polyisocyanate (b) is preferably in the range of 0.3 to 3.00. When the reaction is carried out under conditions where the equivalent ratio exceeds 1, it is preferable to use alcohols such as monofunctional alcohols like methanol, ethanol, propanol, and butanol; or difunctional alcohols consisting of primary and secondary hydroxyl groups like 1,2-propylene glycol and 1,3-butylene glycol, in order to deactivate the terminal isocyanate groups of the urethane (meth)acrylate resin (A) and adjust the equivalent ratio to fall within the aforementioned range.

[0019] Furthermore, when manufacturing the urethane (meth)acrylate resin (A), polymerization inhibitors such as 3,5-di-tert-butyl-4-hydroxytoluene, hydroquinone, methylhydroquinone, hydroquinone monomethyl ether, p-tert-butylcatecholmethoxyphenol, 2,6-di-tert-butylcresol, phenothiazine, tetramethylthiuram disulfide, diphenylamine, and dinitrobenzene may be used as needed; urethane catalysts such as nitrogen-containing compounds such as triethylamine, triethylenediamine, and N-methylmorpholine, metal salts such as potassium acetate, zinc stearate, and tin octoate, and organometallic compounds such as dibutyltin dilaurate may also be used.

[0020] The content of urethane (meth)acrylate resin (A) is preferably in the range of 10 to 90% by mass, more preferably in the range of 20 to 70% by mass, and even more preferably in the range of 25 to 50% by mass, relative to the total amount of the adhesive composition. When the adhesive composition contains urethane (meth)acrylate resin (A) in the above range, the adhesive composition is more likely to achieve a coating viscosity suitable for coating, and the adhesive layer formed from the adhesive composition will have improved cohesive force, resulting in superior adhesion and holding power, as well as superior heat resistance, which is preferable.

[0021] [Nitrogen atom-containing (meth)acrylic monomer (B)] As a nitrogen atom-containing (meth)acrylic monomer (B) capable of forming a homopolymer with a glass transition temperature (Tg) of 15°C or higher, a nitrogen atom-containing (meth)acrylic monomer capable of forming a homopolymer with a Tg of 55 to 160°C is preferred, and a nitrogen atom-containing (meth)acrylic monomer capable of forming a homopolymer with a Tg of 120 to 160°C is more preferred, from the viewpoint that the adhesive layer formed from the adhesive composition will have improved cohesive force, resulting in superior adhesive strength and holding power, as well as excellent heat resistance. Examples of such nitrogen-containing (meth)acrylic monomers include N,N-dimethylacrylamide (119°C), N,N-diethylacrylamide (81°C), N-isopropylacrylamide (134°C), N,N-dimethylaminopropylacrylamide (134°C), acryloylmorpholine (145°C), N-hydroxyethylacrylamide (98°C), N-vinylpyrrolidone (86°C), and N-acryloyloxyethylhexahydrophthalimide. The numbers in parentheses for each monomer represent the Tg of the homopolymer of each monomer as described in, for example, "Polymer Handbook (4th ed.)". These nitrogen-containing (meth)acrylic monomers (B) may be used individually or in combination of two or more. In particular, nitrogen-containing acrylic monomers are preferred from the viewpoint of improving the curability of the adhesive composition, and acryloylmorpholine, N,N-dimethylacrylamide, N,N-dimethylaminopropylacrylamide, and N-acryloyloxyethylhexahydrophthalimide are preferred, with acryloylmorpholine being more preferred, from the viewpoint of the adhesive layer formed from the adhesive composition having improved cohesive force, resulting in superior adhesive strength and holding power, as well as excellent heat resistance.

[0022] Furthermore, the HSP value of nitrogen atom-containing (meth)acrylic monomer (B) is 20 (J / cm²). 3 ) 0.5 Preferably, it is 22 (J / cm²). 3 ) 0.5 It is more preferable that the above is true. The HSP value of nitrogen atom-containing (meth)acrylic monomer (B) is 30 (J / cm²). 3 ) 0.5The following is preferable. If the HSP value of the nitrogen atom-containing (meth)acrylic monomer (B) is within the range described above, a highly polar region derived from the nitrogen atom-containing (meth)acrylic monomer (B) will be present in the adhesive composition, making it easier to exhibit good adhesive properties to highly polar adherends such as metals. Furthermore, it is thought that the polarity of the adhesive composition can be appropriately controlled, and the compatibility of the constituent components, urethane (meth)acrylate resin (A), (meth)acrylic monomer (C), and the tackifying resin (E) described later, will be improved. As a result, it is presumed that the haze of the adhesive composition will be small and the transparency will be excellent, the formed adhesive layer will have better adhesive strength and holding power due to improved cohesive force, and will also have better heat resistance, and that the bleed-out of the tackifying resin (E) from the adhesive layer after curing will be suppressed.

[0023] Here, the HSP value represents the Hansen solubility parameter, and its unit is (J / cm²). 3 ) 0.5 The HSP value is expressed as follows: The solubility parameter (SP value: δ) introduced by Hildebrand is expressed as follows: D , polar term δ P , and hydrogen bonding term δ H These are parameters that take into account the polarity of a substance, represented in three-dimensional space by dividing it into three components, and the following relationship holds true. δ[(J / cm 3 ) 0.5 ]=( δ D 2 +δ P 2 +δ H 2 ) 0.5 The above dispersion term δ D , polar term δ P , and hydrogen bonding term δ HThese parameters have been determined by Hansen and subsequent researchers, and are listed, for example, in the Polymer Handbook (4th edition), VII-698~711. Furthermore, Hansen's solubility parameters for many solvents and resins have been investigated; these parameters are listed, for example, in the Industrial Solvents Handbook (by Wesley L. Archer). They can also be determined using the Hansen Solubility Parameters in Practice (HSPiP) software.

[0024] The dispersion term of the HSP of nitrogen atom-containing (meth)acrylic monomer (B) is 5 (J / cm³). 3 ) 0.5 More than 30(J / cm 3 ) 0.5 Preferably, it is 10 (J / cm²). 3 ) 0.5 More than 25(J / cm 3 ) 0.5 The following is more preferable: The polarity term of the HSP of nitrogen atom-containing (meth)acrylic monomer (B) is 10 (J / cm²). 3 ) 0.5 More than 20(J / cm 3 ) 0.5 Preferably, it is 12 (J / cm²). 3 ) 0.5 More than 18(J / cm 3 ) 0.5 The following is more preferable. Also, the hydrogen bonding term of the HSP of nitrogen atom-containing (meth)acrylic monomer (B) is 5 (J / cm²). 3 ) 0.5 More than 25(J / cm 3 ) 0.5 Preferably, it is 10 (J / cm²). 3 ) 0.5 More than 20(J / cm 3 ) 0.5 The following is even more preferable:

[0025] In the adhesive composition, the content of nitrogen atom-containing (meth)acrylic monomer (B) is preferably in the range of 10 to 300 parts by mass, more preferably in the range of 20 to 200 parts by mass, and even more preferably in the range of 30 to 150 parts by mass, per 100 parts by mass of urethane (meth)acrylate resin (A). When the content of nitrogen atom-containing (meth)acrylic monomer (B) is within the above range, the curability of the adhesive composition can be improved, and the formed adhesive layer tends to have better adhesive strength and holding power, as well as better heat resistance.

[0026] [(meth)acrylic monomer (C)] As a (meth)acrylic monomer (C) capable of forming a homopolymer with a glass transition temperature (Tg) of -15°C or lower, a (meth)acrylic monomer capable of forming a homopolymer with a Tg of -20 to -80°C is more preferred from the viewpoint that the adhesive layer formed from the adhesive composition exhibits superior adhesive strength and holding power. Examples of such (meth)acrylic monomers include ethyl acrylate (-24°C), n-propyl acrylate (-37°C), n-butyl acrylate (-54°C), sec-butyl acrylate (-22°C), isobutyl acrylate (-24°C), 2-ethylbutyl acrylate (-50°C), n-pentyl acrylate (-57°C), isoamyl acrylate (-45°C), n-hexyl acrylate (-57°C), n-heptyl acrylate (-60°C), 2-ethylhexyl acrylate (-70°C), n-octyl acrylate (-65°C), isooctyl acrylate (-58°C), isononyl acrylate (-58°C), isodecyl acrylate (-62°C), lauryl acrylate (-23°C), and acrylic acid. Examples include stearyl acrylate (-58°C), 2-methoxyethyl acrylate (-50°C), 3-methoxypropyl acrylate (-75°C), 2-methoxybutyl acrylate (-32°C), 3-methoxybutyl acrylate (-56°C), 2-ethoxyethyl acrylate (-24°C), 2-ethoxypropyl acrylate (-24°C), 2-ethoxybutyl acrylate (-24°C), 2-hydroxyethyl acrylate (-15°C), 4-hydroxybutyl acrylate (-32°C), ethyl carbitol acrylate (-67°C), phenoxyethyl acrylate (-22°C), 2-hydroxyethyl (meth)acrylate (-15°C), and 4-hydroxybutyl (meth)acrylate (-32°C). The numbers in parentheses for each monomer represent the Tg of the homopolymer of each monomer as described in, for example, "Polymer Handbook (4th ed.)". These (meth)acrylic monomers (C) may be used individually or in combination of two or more types.

[0027] In particular, acrylic monomers are preferred from the viewpoint of improving the curability of the adhesive composition, and n-butyl acrylate, 2-ethylhexyl acrylate, n-octyl acrylate, isooctyl acrylate, and isodecyl acrylate are more preferred from the viewpoint of the adhesive layer formed from the adhesive composition having superior adhesive strength and holding power. Using these acrylic monomers lowers the Tg of the entire adhesive composition, making it easier to achieve good wettability to the adherend.

[0028] Furthermore, the (meth)acrylic monomer (C) is more preferably a monomer that does not have a hydroxyl group, from the viewpoint of improving the handling properties of the adhesive composition, and in particular from the viewpoint of reducing skin irritation and providing excellent safety.

[0029] In the adhesive composition, the content of (meth)acrylic monomer (C) is preferably in the range of 10 to 300 parts by mass, and more preferably in the range of 50 to 200 parts by mass, per 100 parts by mass of urethane (meth)acrylate resin (A). When the content of (meth)acrylic monomer (C) is within the above range, the curability of the adhesive composition can be improved, and the formed adhesive layer tends to have superior adhesive strength and holding power.

[0030] Furthermore, the adhesive composition may contain other vinyl monomers other than the nitrogen atom-containing (meth)acrylic monomer (B) and (meth)acrylic monomer (C) described above, as long as the effects of the present invention are not impaired. Other vinyl monomers include (meth)acrylic acid, N-methylolacrylamide, acrylonitrile, N-vinylformamide, (anhydrous) itaconic acid, (anhydrous) maleic acid, fumaric acid, crotonic acid, carboxyethyl (meth)acrylate, carboxypentyl (meth)acrylate, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate (meth)acrylate t-butyl, n-pentyl methacrylate, isopentyl methacrylate, neopentyl methacrylate, n-hexyl methacrylate, n-heptyl methacrylate, isoheptyl methacrylate, n-octyl methacrylate, isooctyl methacrylate, nonyl methacrylate, cyclohexyl methacrylate, 2-ethylhexyl methacrylate, isobornyl methacrylate, dodecyl methacrylate, f(meth)acrylate Examples include vinyl, glycidyl methacrylate, benzyl (meth)acrylate, trifluoromethylmethyl (meth)acrylate, 2-trifluoromethylethyl (meth)acrylate, 2-perfluoroethylethyl (meth)acrylate, 2-perfluoroethyl-2-perfluorobutylethyl (meth)acrylate, 2-perfluoroethyl (meth)acrylate, perfluoromethyl (meth)acrylate, diperfluoromethylmethyl (meth)acrylate, 2-perfluoromethyl-2-perfluoroethylethyl (meth)acrylate, 2-perfluorohexylethyl (meth)acrylate, 2-perfluorodecylethyl (meth)acrylate, 2-perfluorohexadecylethyl (meth)acrylate, styrene, p-methylstyrene, ethylstyrene, propylstyrene, isopropylstyrene, p-tert-butylstyrene, vinyl acetate, vinyl propionate, vinyl pivalate, etc.

[0031] [Photopolymerization initiator (D)] The photopolymerization initiator (D) generates radicals upon light irradiation or heating, initiating radical polymerization of the urethane (meth)acrylate resin (A), nitrogen atom-containing (meth)acrylic monomer (B), and (meth)acrylic monomer (C). Examples of photopolymerization initiators (D) include acetophenones such as 4-phenoxydichloroacetophenone, diethoxyacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-(4-isopropylphenyl)-2-hydroxy-2-methylpropan-1-one, 1-hydroxycyclohexylphenyl ketone, 4-(2-hydroxyethoxy)-phenyl(2-hydroxy-2-propyl)ketone, 2-methyl-[4-(methylthio)phenyl]-2-morpholino-1-propanone, and 2,2-dimethoxy-2-phenylacetophenone; benzoins such as benzoin, benzoin methyl ether, benzoin isoethyl ether, benzoin isopropyl ether, and benzoin isobutyl ether; benzophenone, benzoylbenzoic acid, methyl benzoylbenzoate, 4-phenylbenzophenone, hydroxybenzophenone, and 4-benzoyl-4'-methyldiphenyl Examples include benzophenones such as rusulfide and 3,3'-dimethyl-4-methoxybenzophenone; thioxanthones such as thioxanthone, 2-chlorothioxanthone, 2,4-dichlorothioxanthone, 2-methylthioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, isopropylthioxanthone, and 2,4-diisopropylthioxanthone; anthraquinones such as 4,4'-dimethylaminothioxanthone, 4,4'-diethylaminobenzophenone, α-acyloxime ester, benzyl, methylbenzoyl formate, and 2-ethylanthraquinone; acylphosphine oxides such as 2,4,6-trimethylbenzoyldiphenylphosphine oxide and bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide; and 3,3',4,4'-tetra(tert-butyloperoxycarbonyl)benzophenone and acrylic benzophenone. These photopolymerization initiators (D) may be used individually or in combination of two or more.

[0032] In particular, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-hydroxycyclohexylphenyl ketone, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, and bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide are preferred from the viewpoint of having excellent compatibility with the nitrogen atom-containing (meth)acrylic monomer (B) and (meth)acrylic monomer (C) used in the present invention, being able to improve the curability of the adhesive composition, and resulting in an adhesive layer that is superior in both adhesive strength and holding power. In the adhesive composition, the content of the photopolymerization initiator (D) is not particularly limited as long as it is in an amount that allows 60% or more by mass of the polymerization components, which include urethane (meth)acrylate resin (A), nitrogen atom-containing (meth)acrylic monomer (B), and (meth)acrylic monomer (C), to be crosslinked. Typically, the range is preferably 0.1 to 20 parts by mass, more preferably 0.5 to 15 parts by mass, and even more preferably 0.5 to 10 parts by mass, per 100 parts by mass of urethane (meth)acrylate resin (A). If the content of the photopolymerization initiator (D) is within the above range, the polymerization components are less likely to remain in an unreacted state, and the remaining unreacted photopolymerization initiator (D) is also reduced, improving the handling properties of the adhesive composition and suppressing performance degradation of the adhesive layer formed from the adhesive composition over time.

[0033] [Adhesion-enhancing resin (E)] The HSP value of the tackifying resin (E) contained in the adhesive composition is 12 (J / cm²). 3 ) 0.5 More than 21(J / cm 3 ) 0.5 The following is the HSP value of the tackifying resin (E): 15 (J / cm²). 3 ) 0.5 More than 21(J / cm 3 ) 0.5 Preferably, it is 16 (J / cm²). 3 ) 0.5 More than 20(J / cm 3 ) 0.5 The following is more preferable. The definition and details of the HSP value are as described above in the explanation of the HSP value of nitrogen atom-containing (meth)acrylic monomer (B). When a tackifying resin (E) with an HSP value within the above-mentioned range is included, the presence of relatively low-polarity regions in the adhesive composition makes it easier to exhibit good adhesive properties to low-polarity substrates such as olefins. Furthermore, the compatibility with the urethane (meth)acrylate resin (A), nitrogen atom-containing (meth)acrylic monomer (B), and (meth)acrylic monomer (C) constituting the adhesive composition is easily improved, making it easier to appropriately control the polarity of the adhesive composition. As a result, the haze of the adhesive composition is small and the transparency is excellent, and the formed adhesive layer exhibits improved cohesiveness, resulting in superior adhesive strength and holding power, as well as superior heat resistance. Moreover, even after the adhesive composition is cured to form an adhesive layer, the bleed-out of the tackifying resin (E) is easily suppressed, resulting in excellent long-term stability of the adhesive layer. In addition, by using a highly polar urethane (meth)acrylate resin (A) and a nitrogen atom-containing (meth)acrylic monomer (B) as adhesive resins, and blending them in a balanced manner with a low-polarity tackifying resin (E) having an HSP value within a specific range, excellent adhesive properties can be achieved for a wide range of substrates. Therefore, in an article to which at least two adherends are bonded via the adhesive tape of the present invention having an adhesive layer formed from such an adhesive composition, the adherends are firmly fixed to each other.

[0034] Furthermore, the softening point of the tackifying resin (E) is preferably 85°C or higher, preferably 90°C or higher, and more preferably 100°C or higher. The softening point of the tackifying resin (E) is preferably 200°C or lower, and more preferably 170°C or lower. When the softening point of the tackifying resin (E) is within the above range, the adhesive layer formed from the adhesive composition exhibits good adhesion at around room temperature (0-40°C) and can demonstrate heat resistance. In this invention, the softening point of the tackifying resin (E) refers to the value obtained by the ring-and-ball method in accordance with JIS K 5902. Furthermore, the acid value of the tackifying resin (E) is preferably 50 mg KOH / g or less, more preferably 30 mg KOH / g or less, and even more preferably 20 mg KOH / g or less. In addition, the hydroxyl value of the tackifying resin (E) is preferably 200 mg KOH / g or less, and more preferably 150 mg KOH / g or less. When the acid value and hydroxyl value are within the above ranges, the tackifying resin (E) tends to have excellent compatibility with urethane (meth)acrylate resin (A), nitrogen atom-containing (meth)acrylic monomer (B), (meth)acrylic monomer (C), etc., and can be used as an indicator to determine polarity as a substitute value even when the HSP value is unknown. The acid value and hydroxyl value of the tackifying resin (E) were measured by titration in accordance with JIS K 0070.

[0035] Examples of tackifying resins (E) include rosin-based, polymerized rosin-based, polymerized rosin ester-based, rosin phenol-based, stabilized rosin ester-based, disproportionated rosin ester-based, hydrogenated rosin ester-based, terpene-based, terpene phenol-based, hydrogenated terpene phenol-based, petroleum resin-based, C5 / C9 petroleum resin-based, process oil, polybutene, polyester-based, and (meth)acrylate-based tackifying resins. These tackifying resins may be used individually or in combination of two or more. Among these, hydrogenated rosin ester-based and hydrogenated terpene phenol-based tackifying resins, which have undergone hydrogenation treatment, are more preferred from the viewpoint of not inhibiting curing by active energy rays. The tackifying resin (E) can be a commercially available product, and a tackifying resin that satisfies the softening point within the aforementioned range and preferably the HSP value within the aforementioned range can be applied as the tackifying resin (E) in the adhesive composition.

[0036] In the adhesive composition, the content of the tackifying resin (E) is preferably in the range of 5 to 200 parts by mass, and more preferably in the range of 10 to 150 parts by mass, per 100 parts by mass of the urethane (meth)acrylate resin (A), from the viewpoint that the adhesive layer formed from the adhesive composition will have excellent adhesive properties such as adhesive strength and holding power, as well as heat resistance, and will also achieve long-term stability. Furthermore, the content of the tackifying resin is preferably in the range of 5 to 50% by mass, and more preferably in the range of 10 to 40% by mass, relative to the entire adhesive composition.

[0037] The adhesive composition may further contain other additives as needed, such as antioxidants, anti-aging agents, colorants such as pigments and dyes, crosslinking agents, thickeners, leveling agents, film-forming aids, infrared absorbers, ultraviolet absorbers, and water repellents, to the extent that they do not impair the effects of the present invention.

[0038] [Adhesive layer] The adhesive composition described above is applied to at least one surface of a foam substrate by a known coating method such as roll coating, knife coating, bar coating, or die coating to form an adhesive layer, which is then cured with active energy rays to form the adhesive layer of the adhesive tape of the present invention. Examples of active energy rays include visible light, ultraviolet light, infrared light, microwaves, EUV, semiconductor laser light, and excimer lasers (KrF, ArF). Among these, curing by irradiation with light such as ultraviolet light is preferred. As light sources such as ultraviolet light, metal halide lamps, xenon lamps, carbon arc lamps, chemical lamps, low-pressure mercury lamps, high-pressure mercury lamps, and UV-LED lamps can be used. From the perspective of generating very little heat and environmental protection that can accommodate mercury-free materials, it is more preferable to cure by light irradiation using a UV-LED lamp, preferably a UV-LED lamp with a main peak wavelength of approximately 365-405 nm that can provide sufficient illuminance. The irradiation energy of light using a UV-LED is 100-5000 mJ / cm². 2 Preferably, it is within the range of 500 to 3000 mJ / cm². 2 A range of 1000 to 2000 mJ / cm² is more preferable. 2 A range of is even more preferable.

[0039] The adhesive compositions described above do not contain crosslinking agents and can form an adhesive layer by curing with active energy rays, thus eliminating the need for aging and significantly contributing to improved productivity of the adhesive tape of the present invention. An adhesive layer made of an adhesive composition, or in other words, an adhesive layer formed by applying an adhesive composition and then cured by the above-mentioned active energy rays, exhibits excellent adhesive strength and holding power, as well as suppressed bleed-out of the adhesive-granting resin (E) and excellent long-term stability. The thickness of the adhesive layer is preferably in the range of 10 to 5 mm, and more preferably in the range of 20 to 2000 μm, from the viewpoint of adhesive retention with the adherend and film uniformity during solution coating. The thickness of the adhesive layer is the average value obtained by measuring the thickness at five arbitrary locations.

[0040] The G' of the adhesive layer at 35°C should be 1.5 × 10⁻⁶, from the viewpoint of achieving good 180° adhesion. 6 Preferably Pa or less, 1.0 × 10 4 ~1.0×10 6 A range of Pa is more preferable, 9.5 × 10 4 ~9.0×10 5 A range of Pa is even more preferable, 1.0 × 10 5 ~8.0×10 5 A range of Pa is particularly preferred. When the 180° adhesion strength and the G' of the adhesive layer at 35°C at each temperature are within the above range, the wettability to the adherend and the elasticity against peeling from the adherend work in a good balance, making it easier to achieve good 180° adhesion strength. The adhesive layer G' can be adjusted by the type, combination, and blending ratio of the urethane (meth)acrylate resin (A), nitrogen atom-containing (meth)acrylic monomer (B), (meth)acrylic monomer (C), photopolymerization initiator (D), and tackifying resin (E) that constitute the adhesive composition. The adhesive layer G' is determined by dynamic viscoelasticity measurement in the examples described later.

[0041] The adhesive tape of the present invention has an adhesive layer formed from the above-described adhesive composition, resulting in excellent adhesive properties such as adhesive strength and holding power, as well as suppressed bleed-out and excellent stability over time. Furthermore, the adhesive tape of the present invention has a low content of volatile components, which reduces adverse effects on the external environment such as smoke generation when fixing objects together or when peeling and dismantling them, and also provides excellent safety for workers during dismantling.

[0042] Foamed base material The foam substrate constituting the adhesive tape of the present invention preferably has a 25% compressive strength of 10 kPa or more. More preferably, the 25% compressive strength of the foam substrate is 12 kPa or more, and even more preferably 15 kPa or more. The 25% compressive strength of the foam substrate is preferably 100 kPa or less, more preferably 80 kPa or less, and even more preferably 60 kPa or less. When the 25% compressive strength of the foam substrate is within the aforementioned range, the adhesive tape of the present invention is more likely to exhibit stress absorption (impact resistance) while ensuring conformability to the adherend. The 25% compressive strength of a foam substrate is determined according to JIS K 6767. A sample of foam substrate cut to 25 mm x 25 mm is used as the measurement sample. The sample is sandwiched between two stainless steel plates with a larger surface area than the measurement sample, and compressed to 75% of its original thickness (i.e., compressed by 25%) at a speed of 10 mm / min in an environment of 23°C. The strength is then measured to determine the strength.

[0043] The apparent density of the foam substrate is 0.05 to 0.75 g / cm³. 3 Preferably, it is 0.1 to 0.5 g / cm³. 3 It is more preferable that the apparent density of the foam substrate is within the above range. If the apparent density of the foam substrate is within the above range, it is easier to adjust the 25% compressive strength, etc., to be within the above range, thereby achieving both stress absorption (impact resistance) and adhesion to the adherend. The apparent density can be measured by measuring the mass of the foam substrate cut into 5cm x 5cm pieces, in accordance with JIS K 6767.

[0044] The tensile elongation at break in the flow direction of the foam substrate is preferably 100% or more, and more preferably 110% or more. The tensile elongation at break in the flow direction is preferably 1000% or less. The tensile elongation at break in the width direction of the foam substrate is preferably 90% or more, and more preferably 100% or more. The tensile elongation at break in the width direction is preferably 800% or less. In the foam substrate constituting the adhesive tape of the present invention, it is preferable that the tensile elongation at break in the flow direction of the foam substrate is 100% or more, and the tensile elongation at break in the width direction of the foam substrate is 90% or more. The tensile breaking strength in the flow direction of the foam substrate is preferably 15 MPa or higher, and more preferably 17 MPa or higher. The tensile breaking strength in the flow direction is preferably 60 MPa or lower, and more preferably 40 MPa or lower. The tensile breaking strength in the width direction of the foam substrate is preferably 10 MPa or more, and more preferably 15 MPa or more. The tensile breaking strength in the width direction is preferably 50 MPa or less, and more preferably 30 MPa or less.

[0045] In the foam substrate constituting the adhesive tape of the present invention, it is preferable that the tensile breaking strength in the flow direction of the foam substrate is 15 MPa or more and 60 MPa or less, and the tensile breaking strength in the width direction of the foam substrate is 10 MPa or more and 50 MPa or less. If the tensile elongation and tensile strength of the foam substrate are within the aforementioned range, the processability and application workability of the adhesive tape of the present invention tend to improve. The tensile elongation and tensile strength of the foam substrate can be measured in accordance with JIS K 6767, using a Tensilon tensile testing machine at 23°C and 50% RH, with a measurement sample of 4 cm in length and 1 cm in width in either the flow direction or the width direction, at a tensile speed of 300 mm / min. The "flow direction" is the direction in which the substrate flows during the foam substrate manufacturing process and is also referred to as "MD," while the "width direction" is the direction perpendicular to the flow direction and is also referred to as "TD."

[0046] The thickness of the foam substrate is preferably 50 to 1500 μm, more preferably 80 to 1200 μm, and even more preferably 100 to 1100 μm. When the thickness of the foam substrate is within the above range, it is easy to form an adhesive tape that is thin and has conformability and stress absorption (impact resistance), which is required for fixing components of electronic devices, especially in small, thin portable electronic devices.

[0047] The material of the foam substrate is not particularly limited as long as it has the above-mentioned 25% compressive strength, apparent density, tensile elongation at break, and tensile strength at break, and examples include polyolefin resins, polyurethane resins, acrylic rubbers, elastomers, etc. Among these, polyolefin resins are preferred, and polyethylene resins are more preferred, from the viewpoint of easily obtaining a foam substrate with excellent conformability to surface irregularities and stress absorption (impact resistance). Examples of polyethylene resins include linear low-density polyethylene, low-density polyethylene, medium-density polyethylene, high-density polyethylene, copolymers of ethylene with α-olefins such as propylene, 1-butene, 4-methyl-1-pentene, 1-hexene, 1-heptene, and 1-octene, and ethylene-vinyl acetate copolymers. Furthermore, polyethylene resins obtained using metallocene compounds containing tetravalent transition metals as polymerization catalysts have a narrow molecular weight distribution, making it easy to obtain a uniformly crosslinked foam substrate. Polyolefin resins may be used individually or in combination of two or more types.

[0048] The foaming ratio of the foam substrate is usually preferably 2 to 10 times, and more preferably 2 to 8 times, from the viewpoint of easily adjusting the 25% compressive strength, apparent density, etc., to the above range, and also easily achieving both stress absorption (impact resistance) and excellent adhesion to the adherend. The foamed substrate is obtained by, for example, supplying a resin composition containing the above-mentioned resin, a thermal decomposition type foaming agent and a foaming aid, and a coloring agent as needed, to an extruder, melting and kneading it, extruding it into a sheet, crosslinking it, then foaming it, and further stretching it in either the flow direction or the width direction, or both, as needed.

[0049] The foam substrate may contain, as needed, colorants, plasticizers, antioxidants, heat stabilizers, flame retardants, antistatic agents, hollow glass or resin particles, fillers such as metal powders or metal compounds, conductive fillers, thermally conductive fillers, etc. The foam substrate may be subjected to surface treatments such as corona treatment, flame treatment, plasma treatment, hot air treatment, ozone treatment, ultraviolet treatment, or application of an easy-adhesion treatment agent, from the viewpoint of improving adhesion with the adhesive layer.

[0050] The adhesive tape of the present invention is preferably a laminate comprising a base layer and an adhesive layer, wherein an adhesive layer made of the aforementioned adhesive composition is provided on one or both sides of a film or sheet-like foam base material. In this case, the thickness of the base material can be appropriately selected according to the purpose, and is usually preferably in the range of 1 μm to 2000 μm.

[0051] If the adhesive tape of the present invention is the laminate described above, such laminate may have a release layer (also called a release sheet or release liner). Examples of release layers include glassine paper, kraft paper, clay-coated paper, paper laminated with a film such as polyethylene, paper coated with a resin such as polyvinyl alcohol or acrylic ester copolymer, and synthetic resin films such as polyester or polypropylene coated with fluororesin or silicone resin. The release layer may be present on one side or both sides of the adhesive tape of the present invention. It is desirable that the release layer installed on the ultraviolet-irradiated surface be made of a material that transmits ultraviolet light sufficient for the curing of the adhesive layer.

[0052] If the adhesive tape of the present invention is the laminate described above, then, in addition to the adhesive layer and the base layer, it may also have other layers such as an insulating layer or a heat insulating layer (for example, a foamed resin layer, a hollow-containing layer, and a hollow particle-containing layer), which are functional layers having functions such as insulating properties, heat insulating properties, impact resistance, waterproofing properties, or heat shielding properties.

[0053] When the adhesive tape of the present invention is the laminate described above, such a laminate can have, but is not limited to, the configurations exemplified below. In the following laminate configurations, " / " represents the lamination interface; for example, "Layer A / Layer B" means that Layer A and Layer B are adjacent, i.e., in direct contact. The base layer refers to the foam base material. ·Adhesive layer / base material layer • Release layer / Adhesive layer / Substrate layer ·Adhesive layer / base material layer / functional layer ·Adhesive layer / functional layer / base material layer • Release layer / Adhesive layer / Functional layer / Substrate layer / Functional layer • Release layer / Adhesive layer / Substrate layer / Adhesive layer ·Adhesive layer / base material layer / adhesive layer ·Adhesive layer / base material layer / functional layer / adhesive layer • Release layer / Adhesive layer / Substrate layer / Adhesive layer / Release layer • Release layer / Adhesive layer / Substrate layer / Functional layer / Adhesive layer • Release layer / Adhesive layer / Functional layer / Substrate layer / Adhesive layer / Release layer • Release layer / Adhesive layer / Functional layer / Substrate layer / Functional layer / Adhesive layer • Release layer / Adhesive layer / Functional layer / Substrate layer / Functional layer / Adhesive layer / Release layer

[0054] There are no particular limitations on the method for manufacturing the adhesive tape of the present invention. For example, if the adhesive tape of the present invention is the laminate described above, the adhesive tape of the present invention can be manufactured by applying the above-mentioned adhesive composition to a foam substrate to form an adhesive layer, placing a release sheet on top of the adhesive layer, and then irradiating it with active energy rays from the release sheet side to form an adhesive layer. Furthermore, by applying the above-mentioned adhesive composition to the opposite side of the foam substrate to form an adhesive layer, placing a release sheet on top, and then irradiating it with active energy rays from the release sheet side to form an adhesive layer, the adhesive tape of the present invention, which is a laminate having adhesive layers on both sides of the foam substrate, can be manufactured. Alternatively, the adhesive tape of the present invention can be manufactured by applying the above-mentioned adhesive composition onto a release sheet to form an adhesive layer, irradiating it with active energy rays to form the adhesive layer, and then bonding the formed adhesive layer to one or both sides of a sheet-like substrate. Furthermore, the adhesive tape of the present invention may be manufactured by applying the above-mentioned adhesive composition to extrusion molding, press molding, injection molding, etc., and then irradiating it with active energy rays.

[0055] When the adhesive tape of the present invention has adhesive layers on both sides excluding the release layer, adherends can be bonded to each side of the adhesive tape, making it suitable for joining adherends together. The adhesive tape of the present invention exhibits excellent adhesive properties such as 180° adhesion (180° peel adhesion), shear adhesion, shear holding power, and push strength to adherents made of a wide range of general-purpose materials. Furthermore, it possesses excellent stress absorption (impact resistance) and heat resistance, making it suitable for bonding rigid adherents to each other. In addition, the adhesive tape of the present invention has a low content of volatile components, reducing adverse effects on the external environment. Therefore, it is suitable for applications used around the human body, specifically as an adhesive tape for fixing components between parts in various products in industrial applications such as electronic equipment, automobiles, building materials, office automation equipment, and home appliances.

[0056] The adhesive tape of the present invention also preferably has a biomass carbon content of 20% or more, more preferably 30% or more, and even more preferably 35% or more, in accordance with ASTM D6866 B. There is no particular upper limit on the biomass carbon content of the adhesive layer. In the adhesive tape of the present invention, the biomass carbon content of the foam substrate constituting the adhesive tape is preferably 30% or more, and more preferably 40% or more, as measured in accordance with ASTM D6866 B. There is no particular upper limit on the biomass carbon content of the foam substrate. Furthermore, the biomass carbon content of the adhesive tape of the present invention, as measured in accordance with ASTM D6866 B, is preferably 20% or more, and more preferably 30% or more. There is no particular upper limit on the biomass carbon content of the adhesive tape of the present invention.

[0057] In this specification, "biomass carbon content (%)" means radioactive carbon ( 14means a corrected value obtained by multiplying the content ratio (pMC%) of C) by 0.93, which is the correction ratio, and when the corrected value is 100% or more, it is regarded as 100%. Here, pMC% refers to radiocarbon in accordance with ASTM D6866 (especially ASTM D6866 Method B) 14 obtained by the C) measurement method.

[0058] 14 C is known to have the property of radioactive decay to nitrogen 14 N). It is constantly generated in an extremely trace amount on the earth by the action of cosmic rays pouring from space, and 14 C is oxidized to carbon dioxide 14 CO2), diffuses into the atmosphere, is then taken into animals and plants during the food chain process, and circulates in the environment through the food chain while decaying in accordance with its half-life. Radiocarbon in accordance with ASTM D6866 Method B 14 C) measurement method is based on the fact that fossil fuels 14 substantially contain no C, while carbon derived from so-called biomass materials (or organisms) contains 14 C absorbed from the atmosphere during their growth period, and this is a method for estimating pMC% from the 14 C ratio in the carbon contained in biomass materials (or organisms). A larger pMC% indicates a lower consumption amount of fossil fuels, and it can be said that the effect of reducing environmental load can be exerted. That is, pMC% is positioned as a value indicating the carbon concentration (mass ratio) of components derived from so-called biomass, which are renewable biological organic resources, and can be used as an indicator indicating the biomass carbon content (%) in other words, the blending ratio of biomass.

[0059] Contained in all carbon atoms of the pressure-sensitive adhesive tape of the present invention 14 By measuring the C content ratio (pMC%), the biomass carbon content (%) can be calculated. In addition, for each of the pressure-sensitive adhesive layer and the foam base material constituting the pressure-sensitive adhesive tape of the present invention, the biomass carbon content (%) of each of the pressure-sensitive adhesive layer and the foam base material can be calculated by similarly measuring pMC%.

[0060] In detail, graphite for pMC% measurement is prepared from adhesive tape, adhesive layer, or foam substrate by a known method. Specifically, the carbon contained in the adhesive tape, adhesive layer, or foam substrate is oxidized and converted entirely into carbon dioxide. After separating the obtained carbon dioxide from water and nitrogen, the carbon dioxide is reduced and converted into graphite, which is solid carbon. Using this graphite as a sample, accelerator mass spectrometry (AMS), which combines a tandem accelerator and a mass spectrometer, is performed to determine the Cs content of the sample. + Negative ions of carbon are generated by irradiating with cations such as the above, and carbon ions are accelerated using a 3MV tandem accelerator, and the charge is converted from negative ions to positive ions, and the isotopes of carbon atoms in the sample (specifically, 12 C, 13 C, 14 C) is analyzed using the mass difference of atoms via an electromagnet. 12 C 3+ , 13 C 3+ , 14 C 3+ By physically separating the orbits of the atoms and measuring the abundance of each individual isotope, 14 C 3+ This can be measured using an electrostatic analyzer. 14 C content (T1) and 12 Calculate the carbon content (T2). Furthermore, the carbon isotopes contained in the obtained graphite 12 C, 13 C and 14 C is accelerated at the same speed, and its flight path is bent by the magnetic field of the mass spectrometer electromagnet. 12 C, 13 C flies inward, the heaviest 14 C flies along the outermost edge of the curved section. 12 C, 13 Because C is abundant, it is detected as a current by a Faraday cup detector. 14 Each C atom is counted individually by an ionization chamber-type ion detector. Separately, oxalic acid (SRM4990C), supplied by the U.S. National Institute of Standards and Technology as a standard material for dating methods, is converted to graphite in the same manner as described above, and the standard material is subjected to the same method as described above. 14 C content (S1) and 12 Determine the C content (S2), and then use the following formula (X) to calculate the radioactive carbon( 14 The content ratio (pMC%) of C) was calculated. pMC%=100×{(T1 / T2) / (S1 / S2)} ···(X)

[0061] Subsequently, the biomass carbon content (%) of the adhesive tape, adhesive layer, or foam will be determined by taking into account the effects of atmospheric nuclear tests from 1950 to the present. The radioactive carbon artificially injected into the atmosphere due to the effects of atmospheric nuclear tests since 1950 ( 14 C) produces approximately 1.5 times the normal amount of radioactive carbon ( 14 Although C) has been observed, it has decreased over time, and the current value is around 107.5 (pMC%), therefore, according to the following formula (Y), radioactive carbon ( 14 The biomass carbon content (%) was calculated by multiplying the content ratio (pMC%) of C) by 0.93 (=100 / 107.5). If this value is 100% or greater, it is considered to be 100%, similar to ASTM. Biomass carbon content (%) = pMC% × 0.93 ···(Y)

[0062] [Goods] The present invention also comprises at least two adherends and an adhesive tape of the present invention having an adhesive layer on both sides of a foam substrate, wherein the two adherends are bonded together via the adhesive tape. The adherend may be rigid or flexible, such as a film. There are no particular restrictions on the material and shape of the adherend; examples include plate-shaped adherends made of resin, glass, or metal, housings, and covers, as well as parts having any of these on their adherend surface. The two adherends bonded together via the adhesive tape may be identical or different. One method for bonding the adherends is to attach each adherend to the adhesive surface of the adhesive tape of the present invention, thereby bonding the two adherends together. There are no particular restrictions on the articles, but from the viewpoint of effectively utilizing the effects of the adhesive tape of the present invention, for example, automotive parts, electronic devices, and parts built into electronic devices are preferred. In a plan view of the article, the adhesive tape may be applied to the entire surface of the object to be adhered, which is the side of the object to which the adhesive tape is applied, or it may be applied to only a part of the surface of the object to be adhered.

[0063] Although one embodiment of the adhesive tape and article of the present invention has been described above, the present invention is not limited to the configuration of the embodiment described above. For example, the adhesive tape and article of the present invention may have additional configurations of any other choice in the configuration of the above embodiment, or may be replaced with any configuration that produces a similar effect. [Examples]

[0064] The present invention will be specifically described below with reference to examples. However, the present invention is not limited to the examples described below. The materials used in these examples are shown below.

[0065] 《Urethane (meth)acrylate resin (A)》 [Synthesis Example 1] Polypropylene glycol and 2-hydroxyethyl acrylate were added to a reaction vessel equipped with a stirrer, reflux condenser, nitrogen inlet tube, and thermometer. The internal temperature was raised to 40°C, isophorone diisocyanate was added, and the temperature was raised to 80°C over 1 hour, followed by stirring at 80°C for 12 hours. After confirming that the isocyanate groups in the reaction mixture had disappeared, the mixture was cooled to obtain resin A1 as urethane (meth)acrylate resin (A). The obtained resin A1 had an acryloyl group equivalent of 26,500, a Mw of 53,000, and a Tg of -61°C.

[0066] [Synthesis Example 2] Polypropylene glycol and 2-hydroxyethyl acrylate were added to a reaction vessel similar to that used in Synthesis Example 1. The polypropylene glycol used was produced from glycerol via 3-hydroxypropyl aldehyde (HPA) by a fermentation method that decomposes plant raw materials to obtain glucose. The internal temperature was raised to 40°C, isophorone diisocyanate was added, and the temperature was raised to 80°C over 1 hour, followed by stirring at 80°C for 12 hours. After confirming that the isocyanate groups in the reaction mixture had disappeared, it was cooled to obtain resin A2 as urethane (meth)acrylate resin (A). The obtained resin A2 had an acryloyl group equivalent of 9500, a Mw of 19000, and a Tg of -65°C. Furthermore, the biomass content of resin A2 was 80%.

[0067] [Synthesis Example 3] Polypropylene glycol and 2-hydroxyethyl acrylate were added to a reaction vessel similar to that used in Synthesis Example 1. The polypropylene glycol used was produced from glycerol via 3-hydroxypropyl aldehyde (HPA) by a fermentation method that decomposes plant raw materials to obtain glucose. The internal temperature was raised to 40°C, isophorone diisocyanate was added, and the temperature was raised to 80°C over 1 hour, followed by stirring at 80°C for 12 hours. After confirming that the isocyanate groups in the reaction mixture had disappeared, it was cooled to obtain resin A3 as urethane (meth)acrylate resin (A). The obtained resin A3 had an acryloyl group equivalent of 35,000, a Mw of 70,000, and a Tg of -66°C. Furthermore, the biomass content of resin A3 was 85%.

[0068] [Synthesis Example 4] In a reaction vessel similar to that used in Synthesis Example 1, a polyester polyol obtained using a mixture of adipic acid and isophthalic acid as the acid component, and a mixture of 1,3-propanediol and 3-methyl-1,5-pentanediol as the diol component, was added, along with N-(2-hydroxyethyl)acrylamide. The internal temperature was raised to 40°C, trimethylhexamethylene diisocyanate was added, and the temperature was raised to 80°C over 1 hour, followed by stirring at 80°C for 12 hours. After confirming that the isocyanate groups in the reaction mixture had disappeared, the mixture was cooled to obtain resin A4 as urethane (meth)acrylate resin (A). The obtained resin A4 had an acryloyl group equivalent of 10,000, Mw of 20,000, and Tg of -32°C.

[0069] 《Nitrogen atom-containing (meth)acrylic monomer (B)》 Monomer B1: Acryloylmorpholin (HSP value of the monomer: 22.3 (J / cm²)) 3 ) 0.5 (Tg 145℃ during homopolymer formation) Nitrogen-containing polymerizable monomers Monomer B': N-vinylpyrrolidone (HSP value of the monomer: 19.2 (J / cm³) 3 ) 0.5 (Tg 86℃ during homopolymer formation) (Meth)acrylic monomer (C) Monomer C1: n-octyl acrylate (Tg -65℃ during homopolymer formation) Photopolymerization initiator (D) Initiator D1: "Omnirad184" (trade name, manufactured by IGM RESINS BV, 1-hydroxycyclohexylphenyl ketone)

[0070] 《Adhesion-enhancing resin (E)》 The following commercially available products were used. The HSP values ​​of each product were measured using the Hansen sphere method. Tackifying resin E1: "YS Polystar TH130" (product name, manufactured by Yasuhara Chemical Co., Ltd., terpene phenol resin, softening point 125-135°C, HSP value 18.0 (J / cm) 3 ) 0.5(65% biomass content) Tackifying resin E2: "YS Polystar UH115" (product name, manufactured by Yasuhara Chemical Co., Ltd., terpene phenol resin, softening point 110-120°C, HSP value 17.7 (J / cm) 3 ) 0.5 (65% biomass content) Tackifying resin E3: "YS Polystar G125" (product name, manufactured by Yasuhara Chemical Co., Ltd., terpene phenol resin, softening point 120-130°C, HSP value 18.5 (J / cm)) 3 ) 0.5 (55% biomass content) Tackifying resin E4: "Haritack F85" (product name, manufactured by Harima Chemicals Co., Ltd., rosin-based resin, softening point 93-101°C, HSP value 20.0 (J / cm²) 3 ) 0.5 , 100% biomass) Tackifying resin E5: "Reactol UV-2000R", polyester resin, manufactured by LAWTER, softening point 120°C, HSP value 22.6 (J / cm²) 3 ) 0.5 , Biomass content 0%)

[0071] 《Base material》 The following commercially available products were used. The characteristics of substrates A to D are shown in Table 1. Substrate A: "Volara (registered trademark) #05002" (product name, manufactured by Sekisui Chemical Co., Ltd.) Base material B: "Volara (registered trademark) #05502" (product name, manufactured by Sekisui Chemical Co., Ltd.) Base material C: "Emblet (registered trademark) S-25" (product name, manufactured by Unitika Corporation) Base material D: "D-54G" (product name, manufactured by Nippon Paper Papilia Co., Ltd.)

[0072] [Table 1]

[0073] 1. Example of preparation of an active energy ray-curable adhesive composition Manufacturing Example 1 Adhesive composition 1 was obtained by mixing 100 parts by mass of resin A1 as urethane (meth)acrylate resin (A), 60 parts by mass of monomer B1 as nitrogen atom-containing (meth)acrylic monomer (B), 90 parts by mass of monomer C1 as (meth)acrylic monomer (C), 1 part by mass of initiator D1 as photopolymerization initiator (D), and 100 parts by mass of tackifying resin E1 as tackifying resin (E).

[0074] Production examples 2~11, C1~C6 Adhesive compositions 2-11 and C1-C6 were obtained in the same manner as in Production Example 1, except that the components and their amounts were changed as shown in Table 1.

[0075] 2. Examples of double-sided adhesive tape manufacturing Example 1 (1) The adhesive composition 1 obtained in Manufacturing Example 1 was applied to the surface of a release-treated polyethylene terephthalate film (release PET 75) with a thickness of 75 μm so that the film thickness after UV irradiation was 75 μm, and another release PET 75 was bonded onto the coated surface. Then, from above the release PET 75, a UV irradiation device was used to irradiate the film with an integrated light amount of 1400 mJ / cm² at wavelengths of 300-390 nm. 2 By irradiating with ultraviolet light under these conditions, an adhesive sheet 1 was fabricated in which two release PET75 sheets were laminated with an adhesive layer in between. (2) The release PET 75 on one side of the adhesive sheet obtained in (1) above was peeled off to expose the adhesive layer, and one sheet was attached to each side of the base material A (polyolefin foam, thickness 200 μm, foaming ratio 6 times, 25% compressive strength 55 kPa, tensile breaking strength in the width direction (TD) 3.2 MPa, tensile breaking strength in the length direction (MD) 4.6 MPa, surface treated with corona to achieve a wettability index of 60 mN / m), and then laminated with a roll heated to 90°C and with a linear pressure of 5 kg / cm to obtain a double-sided adhesive tape 1 with a thickness of 350 μm.

[0076] Examples 2-11, Comparative Examples 1-6 In Example 1, adhesive compositions 2-11 and C1-C6 obtained in Production Examples 2-11 and C1-C6 were used instead of adhesive composition 1, and the substrates shown in Table 2 were used instead of substrate A. In the same manner as in Example 1, double-sided adhesive tapes 2-11 and C1-C6 were obtained.

[0077] 3. Evaluation 3-1. 180° Adhesion (180° Peel Adhesion) (1) One of the release PET75 layers constituting the double-sided adhesive tape obtained in each example and comparative example was peeled off, and a polyethylene terephthalate film (PET25) with a thickness of 25 μm was bonded to the surface of the adhesive layer to create an adhesive film (laminated structure), and this adhesive film (laminated structure) was cut to a width of 20 mm to make an adhesive tape. (2) The release PET75 was peeled off the adhesive tape, and the surface of the adhesive layer was attached to a stainless steel plate (SUS304 with a hairline finish using #360 sandpaper). A 2kg roller was passed back and forth once over the top surface of the adhesive tape, and the test specimen was left to stand for 1 hour in an environment of 23°C and 50%RH to create a test specimen in which the adhesive tape and the stainless steel plate were pressed together. Next, using a Tensilon tensile testing machine, with the stainless steel plate constituting the test specimen fixed, the strength was measured when the adhesive tape was peeled off in the 180° direction at a tensile speed of 300 mm / min, and this was defined as the 180° adhesive force to the stainless steel plate. (3) In the same manner as in (2) above, a test piece was prepared and peeled in the 180° direction, except that a polypropylene plate (Showa Denko Materials Co., Ltd., "PP-N-BN") was used instead of a stainless steel plate. The strength was measured and this was defined as the 180° adhesive strength to the polypropylene plate.

[0078] 3-2. Shear Adhesion (1) The double-sided adhesive tapes obtained in each example and comparative example were cut into squares measuring 20 mm in length and 20 mm in width. The release PET75 on both sides was peeled off, and the adhesive layers on both sides were attached to stainless steel plates (SUS304 steel plates). A 2 kg roller was passed back and forth once on the upper surface of one of the stainless steel plates to apply pressure and adhesion. The pieces were then left to stand for 24 hours in an environment of 23°C to prepare the test specimens. Next, using a Tensilon tensile testing machine, the adhesive strength was measured when both stainless steel plates constituting the test specimen were pulled in the shear direction at a tensile speed of 10 mm / min under conditions of 23°C, and this was defined as the shear adhesive strength to the stainless steel plates. (2) A test specimen was prepared in the same manner as in (1) above, except that a polypropylene plate (Showa Denko Materials Co., Ltd., "PP-N-BN") was used instead of a stainless steel plate. The adhesive force was measured when both polypropylene plates constituting the test specimen were pulled in the shear direction at a tensile speed of 10 mm / min, and this was defined as the shear adhesive force to the polypropylene plate.

[0079] 3-3. Shear holding capacity One side of the release PET75 was peeled off from the double-sided adhesive tape obtained in each example and comparative example. The surface of the adhesive layer was backed with 50 μm thick aluminum foil under conditions of 23°C and 50% RH, and the tape was cut to a length of 100 mm and a width of 20 mm. The release PET75 was peeled off from the cut adhesive tape, and the surface of the adhesive layer was bonded to a stainless steel plate (SUS304 with a hairline finish using #360 sandpaper) with an adhesive area of ​​20 mm x 20 mm (4 cm). 2 The adhesive tape was attached in such a manner, and a 2kg roller was passed back and forth once over the upper surface of the cut adhesive tape. The test piece was then left to stand for 1 hour in an environment of 23°C and 50%RH to create a test piece in which a portion of the cut adhesive tape and the stainless steel plate were pressed together. Next, the stainless steel plate side of the test specimen was fixed to a force meter in a 70°C environment. Then, the portion of the cut adhesive tape on the test specimen that was not attached to the stainless steel plate was folded over, a 500g weight was attached, and the specimen was left in a 70°C environment. The time until the cut adhesive tape peeled off (fell) was measured. If it was held for 1440 minutes, the test was terminated at that point.

[0080] 3-4. Push strength The double-sided adhesive tapes obtained in each example and comparative example were cut into window frame shapes with outer dimensions of 14 mm square and width of 2 mm. Under conditions of 23°C and 50% RH, the release PET 75 on one side of the double-sided adhesive tape was peeled off, and one piece of the adhesive tape was attached to an acrylic plate (manufactured by Mitsubishi Chemical Corporation, "Acrylite L (product name)") measuring 2 mm thick x 40 mm long x 65 mm wide, so that the center of the window frame-shaped processed product and the center of the acrylic plate overlapped, to create a test specimen. The release PET 75 on the other side of this test specimen was peeled off, and it was attached to the surface of a stainless steel plate with a 10 mm diameter hole in the center (adhesion area 0.96 cm²). 2 ), 50 N / cm from above the glass plate 2 The adhesive was obtained by applying pressure for 10 seconds. The obtained adhesive samples were left for 24 hours in an atmosphere of 23°C and 50%RH. Next, using a Tensilon tensile testing machine, a glass plate was pushed through a hole in the stainless steel plate of the adhesive sample using a 7mm diameter SUS probe at a speed of 10mm / min in an environment of 23°C, and the strength at which the glass plate peeled off was measured and defined as the push strength.

[0081] 3-5. Storage modulus (G') In each example and comparative example, two release PET75 sheets were peeled off from the adhesive sheet, which consisted only of the adhesive layer formed during the production of the double-sided adhesive tape, to separate the adhesive layer. This adhesive layer was then stacked to a thickness of approximately 2 mm, and then punched out into a circular shape with a diameter of 8 mm to obtain a test specimen. A viscoelasticity tester (ARESG2, manufactured by TA Instruments Japan) was fitted with an 8mm diameter parallel plate, the above test specimen was placed between the plates, and measurements were taken from 30°C to 200°C at a frequency of 1Hz and a heating rate of 5°C / min to determine the storage modulus at each temperature. The value at 35°C was adopted.

[0082] 3-6. Biomass carbon content The double-sided adhesive tapes, adhesive layers, and foam substrates obtained in each example were subjected to an oxidation treatment to convert them all into carbon dioxide. After separating the resulting carbon dioxide from water and nitrogen, the carbon dioxide was subjected to a reduction treatment to convert it into graphite, which is solid carbon. Using such graphite as a sample, accelerator mass spectrometry (AMS), which combines a tandem accelerator and a mass spectrometer, is performed to determine the presence of Cs in the sample. + Negative ions of carbon are generated by irradiating with cations such as the above, and carbon ions are accelerated using a 3MV tandem accelerator, and the charge is converted from negative ions to positive ions, and the isotopes of carbon atoms in the sample (specifically, 12 C, 13 C, 14 C) is analyzed using the mass difference of atoms via an electromagnet. 12 C 3+ , 13 C 3+ , 14 C 3+ By physically separating the orbits of the atoms and measuring the abundance of each individual isotope, 14 C 3+ This can be measured using an electrostatic analyzer. 14 C content (T1) and 12 The C content (T2) was calculated. Separately, oxalic acid (SRM4990C), supplied by the U.S. National Institute of Standards and Technology as a standard material for dating methods, is converted to graphite in the same manner as described above, and the standard material is subjected to the same method as described above. 14 C content (S1) and 12 Determine the C content (S2), and then use the following formula (X) to calculate the radioactive carbon( 14 The content ratio (pMC%) of C) was calculated, and the biomass carbon content (%) was determined using the following formula (Y). If the resulting value was 100% or more, it was set to 100%. pMC%=100×{(T1 / T2) / (S1 / S2)} ···(X) Biomass carbon content (%) = pMC% × 0.93 ···(Y)

[0083] The results described above are summarized in Table 2. The adhesive tape formed from the adhesive composition satisfying the provisions of the present invention exhibits excellent and well-balanced adhesive properties such as 180° adhesion, shear adhesion, shear holding power, and push strength, and also exhibits excellent long-term stability of the adhesive layer. Furthermore, the biomass carbon content of the adhesive tape, adhesive layer, and foam substrate is 20% or more, positioning it as a product that reduces environmental impact.

[0084] [Table 2] [Industrial applicability]

[0085] The adhesive tape of the present invention exhibits excellent adhesive properties to a wide range of general-purpose materials with varying polarities, such as metals and polyolefins. It also possesses stress absorption capabilities (impact resistance) that can absorb stress between parts and products, and has excellent heat resistance. Therefore, the adhesive tape of the present invention can be suitably used as an adhesive tape for fixing parts between various products in industrial applications such as electronic equipment, automobiles, building materials, office automation equipment, and home appliances.

Claims

1. An adhesive tape comprising a foam substrate and an adhesive layer provided on at least one surface of the foam substrate, The adhesive layer contains an active energy ray curable adhesive composition, The above-mentioned active energy ray curable adhesive composition is A urethane (meth)acrylate resin (A) having an acryloyl group equivalent of 5,000 to 40,000, obtained by reacting a polyol (a), a polyisocyanate (b), and a (meth)acrylic compound (c) having hydroxyl groups, A nitrogen atom-containing (meth)acrylic monomer (B) capable of forming a homopolymer with a glass transition temperature of 15°C or higher, A (meth)acrylic monomer (C) capable of forming a homopolymer with a glass transition temperature of -15°C or lower, Photopolymerization initiator (D), HSP value is 12 (J / cm²) ３ ) ０．５ Above 21 (J / cm ３ ) ０．５ An adhesive tape containing the following tackifying resin (E).

2. The adhesive tape according to claim 1, wherein the urethane (meth)acrylate resin (A) is a polyether-based urethane (meth)acrylate resin or a polyester-based urethane (meth)acrylate resin.

3. The adhesive tape according to claim 1, wherein the weight-average molecular weight (Mw) of the urethane (meth)acrylate resin (A) is 15,000 or more.

4. The adhesive tape according to claim 1, wherein the softening point of the tackifying resin (E) is 90°C or higher.

5. The HSP value of the tackifying resin (E) is 15 (J / cm²). ３ ) ０．５ Above 21 (J / cm ３ ) ０．５ The adhesive tape according to claim 1, which is as follows:

6. The HSP value of the nitrogen atom-containing (meth)acrylic monomer (B) is 20 (J / cm ３ ) ０．５ or more, the pressure-sensitive adhesive tape according to claim 1.

7. The adhesive tape according to claim 1, wherein the (meth)acrylic monomer (C) is a monomer that does not have a hydroxyl group.

8. The adhesive tape according to claim 1, wherein the biomass carbon content of the adhesive layer, as measured in accordance with ASTM D6866 B method, is 20% or more.

9. The adhesive tape according to claim 1, wherein the 25% compressive strength of the foam substrate is 10 kPa or more.

10. The apparent density of the foam substrate is 0.05 to 0.75 g / cm³. ３ The adhesive tape according to claim 1.

11. The adhesive tape according to claim 1, wherein the tensile elongation at break in the flow direction of the foam substrate is 100% or more, and the tensile elongation at break in the width direction of the foam substrate is 90% or more.

12. The adhesive tape according to claim 1, wherein the tensile breaking strength of the foam substrate in the flow direction is 15 MPa or more and 60 MPa or less, and the tensile breaking strength of the foam substrate in the width direction is 10 MPa or more and 50 MPa or less.

13. The adhesive tape according to claim 1, wherein the biomass carbon content of the foam substrate, as measured in accordance with ASTM D6866 B method, is 30% or more.

14. The adhesive tape according to claim 1, wherein the biomass carbon content of the adhesive tape, as measured in accordance with ASTM D6866 B method, is 20% or more.

15. An article comprising at least two adherends and an adhesive tape according to claim 1, having the adhesive layer on both sides of the foam substrate, wherein the two adherends are bonded together via the adhesive tape.

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